Large-mass single-electron-resolution detector for dark matter and neutrino elastic interaction searches

Large mass single-electron-resolution solid state detectors are desirable to search for low mass dark matter candidates and to measure coherent elastic neutrino nucleus scattering (CE$ u$NS). Here, we present results from a novel 100 g phonon-mediated Si detector with a new interface architecture. This detector gives a baseline resolution of $sim 1 e^{-}/h^{+}$ pair and a leakage current on the order of $10^{-16}$ A. This was achieved by removing the direct electrical contact between the Si crystal and the metallic electrode, and by increasing the phonon absorption efficiency of the sensors. The phonon signal amplification in the detector shows a linear increase while the signal to noise ratio improves with bias voltage, up to 240 V. This feature enables the detector to operate at a low energy threshold which is beneficial for dark matter and CE$ u$NS like searches.